JPH02182702A - Manufacture of ethylene polymer - Google Patents

Abstract

The invention relates to a process for the preparation of low-pressure ethylene polymers by polymerising the monomers in the presence of a Ziegler catalyst system, in which process the solid ethylene polymer obtained is reacted in the melt with additives which are able to form acids by esterification. The ester-forming additives are preferably epoxide compounds.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention describes the use of a Ziegler catalyst system, in particular a catalyst system consisting of vanadium, an organoaluminum and an organohalide, in a polymerization zone at a pressure of 5 to 60 bar and a temperature of up to 120°C. The monomers are combined in the presence of a stirred or vortex drying phase or in a low-boiling hydrocarbon as a suspending agent, and after depressurization in a depressurization zone, the resulting solid ethylene polymer is removed from the unreacted tops and optionally. Separated from the suspending agent and monomer and optionally by introduction of an inert gas stream in the degassing zone! ! ! The present invention relates to a method for producing ethylene polymer by removing residual portions of clouding agent and transferring solid ethylene polymer to a melt sphere.

(Prior Art) Unpolymerized monomers and other accompanying substances deteriorate the quality of the resulting polymer due to their inherent odor and therefore need to be removed. Ethylene polymer, accompanying monomers, malodorous substances or! ! ! Methods of purification by separation of clouding agents or solvents have been known for a long time. For example, removing liquid hydrocarbons using a stream of inert gas such as carbon dioxide or nitrogen (U.S. Pat. Nos. 3,152,872, 4,258,158)
No. 4372758, European Patent Application Publication 127
253), washing the target product with liquid olefin (US Pat. No. 4,214,063), or degassing the polyolefin powder with saturated aliphatic hydrocarbons (Chemical Abstracts 103.1958.54599r). It is.

West German patent applications P 3735937 and P 38154
In No. 87, as a method for removing the suspending agent and unreacted sulfur, the remaining portions are introduced into a deaeration zone (also called a dry bombing zone) through a depressurization zone, and are filled with an inert gas. It has been proposed to remove by introducing a stream or by washing first with ethylene and then with a mixture of nitrogen and steam.

The technical problem in this field is therefore to provide a method for producing ethylene polymers which do not emit bad odors using Ziegler catalyst systems, especially vanadium-containing catalyst systems.

(Summary of the Invention) However, the above-mentioned technical problem is based on the method in the above (Technical Field) section, in which the produced ethylene polymer is heated in a melting zone, preferably in an extruder at 170 to 280°C, preferably at 0.5°C. It has been found that M can be determined by the process of the invention, which is characterized in that it is reacted with 0.2 to 2% by weight of an additive capable of binding acids by esterification, in particular an organic ebony compound.

(Structure of the Invention) The method itself described in the above section of the prior art is publicly known, and the details of this method are described in various documents (for example, "Ullmans, Eretzikropedie,
Dell, Teichnischen, Hemi-J 1980 4th edition,
! 98. pp. 178-186 or "Encyclopedia of Polymer Science and Engineering J 1986 2nd edition, 68.436-43
(See page 8). In the present invention, the term ethylene polymer refers to
Homopolymers of ethylene as well as copolymers of a predominant amount of ethylene with other α-olefins are meant.

The substances to be used in the process of the invention are customary. The same applies to the monomers, in particular ethylene, and the comonomers propylene, butene-1, hexene-1,4-methylpentene-1 or octene-1, and optionally. Ru! ! Low-boiling hydrocarbons, especially zero
Saturated hydrocarbons from 3 to c8 are preferred. The comonomer m to be polymerized and contained in the ethylene polymer is 1 to 20% by weight. Preference is also given to conventional vanadium-containing catalyst systems of the Ziegler type, such as those which are the subject of European Patent Application No. 166,888. The same applies to the inert gas used for post-cleaning of the solid phase.

The separation of the solid ethylene polymer and the unreacted gaseous monomer is achieved by converting the mixture into a tank for discharge, at a pressure of 0.1 to 3 bar, preferably 1 to 1.2 bar, at a temperature of 40 to 120°C. This is done by continuously discharging the gas into a depressurized zone that is maintained at a temperature of . Here, a gas phase consisting of ligneous monomers and a solid consisting essentially of an ethylene polymer and containing from 0, 1 to 8% by weight of accompanying monomers and optionally a separated 2g agent, based on this polymer, are present. phase is formed.

The monomers separated from the polymer and the optionally separated suspending agent are preferably fed back into the building.

For further details, reference is made to the documents cited at the outset, and in particular to European Patent Application No. 174,620.

By known methods, the solid ethylene polymer is discharged from the degassing zone and fed to the melting zone (generally located in an extruder).

The ethylene polymer obtained by the method described in the prior art section has a weight of 0.940 to 0.960 g/cm
It exhibits a density of 3 and a melt index of 1 to 300 g/min. The polymer particles, which still contain unreacted monomers and optionally residual fractions of suspended agents, are discharged from the depressurization zone and transferred to the degasification zone, which is maintained at a pressure of 1 to 1.2 bar. (can also be sent to) The temperature in this degassing zone is maintained at 65 to 80° C., and dry explosion is automatically carried out by an inert gas flow in a spiral dryer, for example.

Particularly suitable inert gases are nitrogen or carbon dioxide (see German patent application P 3735937.1).

According to the method of the invention, the ethylene polymer is prepared in the melt zone, in particular in the extruder, at a temperature of 170 to 280°C.
By esterification, it is reacted with an additive capable of binding an acid, preferably an aliphatic epoxide compound. This additive is preferably used in an amount of 0.02 to 2% by weight, based on the ethylene polymer. Examples of suitable organic epoxide compounds are epoxidized soybean oil and other epoxidized fats and oils, as well as glycidyl compounds, such as glycidyl propionate. Such additives are incorporated and reacted with the ethylene polymer in a separate mixer with mixers well known in the art or in the melt zone of an extruder.

An advantage of the process of the invention is that it is possible to produce ethylene polymers which are significantly improved in terms of odor by the Ziegler polymerization process, which improvement is demonstrated by the malodor test method according to DIll 10955.

EXAMPLE (A) Copolymer of Ethene and Butene-(1) This copolymerization is carried out continuously in a conventional loop reactor, such as that shown, for example, in U.S. Pat. No. 3,242,150. The circulation tube of this reactor has an inner diameter of 0.15 m and an extended length of 11.4 m.

This reactor performs continuous-static processing in the following manner.

(a) Isobutane was used as reaction medium.

(b) The amount of ethylene monomer in the reaction mixture was constantly maintained at 25% by volume.

(C) The amount of butene-(1) monomer in the reaction mixture was constantly maintained at 4% toxicity.

(d) The amount of hydrogen in the reaction mixture was constantly maintained at 0.15% by volume.

(e) Ziegler catalyst systems include those covered by European Patent Application No. 166888, namely (1) a transition metal composition as described in the Examples of the above-mentioned publication; (2) aluminum triisobutyl; and (3) ) The catalyst composition consists of trichloromonofluoromethane, and the ratio of the transition metal of the catalyst composition (1) to the aluminum molecule of the component (■) is 1:5.63, and the molecular ratio of the composition (■) to the aluminum molecule of the component (3) is 1:0.11. A constantly maintained catalyst system was used.

A guideline for the absolute amounts of these catalyst components was to maintain the aluminum triisobutyl concentration in the reaction mixture at 135 μg per kg of imbutene.

(f) At a copolymerization reaction temperature of 80° C., the pressure of the reaction mixture was approximately 40 bar.

(g) The reaction mixture was circulated at a rate of 811/s.

(h) The average median concentration of polymer in the recycle stream, CIl, is adjusted to $(tr,
I did it.

(i) The produced polymer was taken out from the reaction mixture outlet at an intermediate point between the lowermost and uppermost parts of the circulation tube.

The polymer concentration Cm in here 4 was 0.59, which corresponds to 0.32 g of polymer per 1 g of reaction mixture.

In this way, 19.5 kg of copolymer was obtained per hour,
Its melt index is 165 g/10m1n
(measured at 190°C/21.6 kg according to DIN 53735), density 0.949 g/cm3 (DIN 5
3457), the average particle size is 0.95. , (DIN53
477), the bulk density is 495 g/cvs3 (DI
ll 53468).

(B) Production process (1,1) of the transition metal composition (1) of the catalyst used in the above-mentioned copolymerization 25 weight R silicon dioxide (Sift, particle size 20 60μ
mt pore volume 1.75 cm'/g 1 surface area 3401
27 g), 100 parts by weight of tetrahydrofuran, 1000 parts by weight of a transition metal (panadium trihalogenide/alcohol complex compound vc13.4 ZO■ (Z represents an isopropyl group t), 100 parts by mole of titanium trihalogenide WTiC13-1 /3 (consisting of 1.3 mole parts of ALCl and 6.7 mole parts of zirconium tetrachloride). Both of the above components were combined and the resulting suspension was stirred for a while. The product solid phase was then subjected to a pressure of 10
Separation is effected by sputtering the rotary evaporator liquid fraction at mbar and a temperature of 70°C.

Steps (1, 2) 20 parts by weight of the solid phase obtained in steps (1, 1) were suspended in 160 parts by weight of n-heptane, and 8 parts by weight of diethylaluminum chloride in 20 mfnK of n-heptane was added to this suspension.
Parts by weight of the solution were added and the resulting suspension was briefly stirred at 65°C. It was then filtered, washed three times with n-hebutane and dried under vacuum.

When the solid phase product, ie, catalyst composition (1), was analyzed, it was confirmed that it contained 0.00156 mol/g of transition metal.

(C) Reaction of the produced copolymer with the epoxide compound (
By reducing the pressure of the copolymer obtained in A) to 1 bar! Separated from a abrasive agent and liquid used material. Furthermore, the residual portion of the liquid substance is removed by a nitrogen gas flow at I51:t'.
p was removed. The particulate copolymer thus obtained was mixed with 2000 ppm of Stair 1J Calcium heptaate, IOooppmOIrganox"+07 in a mixing tank.
6 (sterically-damaged phenolic antioxidant from Ciba Geigy) and 200 ppm of Edenol D81 (epoxidized soybean oil from Henkel), using a -screw extruder (diameter 2011 length 200, extrusion rate 1 customer/h). ),
It was made into granules.

The same process as in the above-mentioned inventive example was repeated, except that the epoxidized soybean oil in Example 1 (C) was not used.

The resulting polymers obtained according to the above examples of the invention showed an improvement of 1.5 units in the malodor test according to DIN 10955 over the comparison polymers.

Representative Patent Attorney Osamu Myo

Claims (1)

[Claims] polymerizing the monomers in a polymerization zone at a pressure of 5 to 60 bar and a temperature of up to 120° C. in the presence of a Ziegler catalyst system in a stirred or vortex drying phase or in a low-boiling hydrocarbon as a suspending agent; After depressurization, the solid ethylene polymer produced is separated from unreacted monomers and optionally suspending agent in a degassing zone, and residual parts of monomer and optionally suspending agent are removed in a degassing zone by introducing a stream of inert gas. A method for producing an ethylene polymer by transferring a solid ethylene polymer to a melting zone, characterized in that the ethylene polymer is reacted with an additive capable of binding to an acid by esterification in the melting zone. Method.